keeping straight wall bed leg with shelf

check this video CityLine - YouTube

what mechanism is used to keep wall bed legs vertical ,so that the things kept on wall bed legs shelf do not fall ?

if it is weighted right I think it could be accomplished with gravity.

gravity alone can’t accomplish this ,even a little bit of weight of shelf and the leg won’t be vertical
also the it would swing and things would fall


It looks like it has a single pivot on the bed end of the arm, so adding more weight would make it more likely to sit vertical and less likely to swing, no?

Murphy bed mechanisms have been around forever. See how the leg works in the pic. Just hide the link in the side frame.

Side note, who was Murphy and why did he get a bed named after him (or her)?

Wiki is your friend.

Man… if only that existed when I was in college…